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Post by gadget on Jul 3, 2019 19:58:57 GMT -8
I have been heating my house with in-floor pex for twenty years. I have a built in wood heater with a somewhat convoluted smoke path and I use two three quarter inch black iron pipe grids in the back of the stove. Each one feeds a storage tank above the stove. One is a full sized oxygen tank and the other a hundred pound propane tank. These are both open to the atmosphere by slightly cracking the valves so no pressure builds. The tanks rely on pumps to move the water though the pex in the floors and it keeps the temps in the tanks within limits while they are running but even if they are not and the water in the tanks hits the boiling point there is no danger and they just vent off the steam. The water feeds from the bottom of the tanks to the bottom of the pipe grids and then thermosyphons back to the top of the tanks. I'm just mentioning all this to show that a hot water heating system can be operated perfectly safely over a long period of time. Hey dirtdevil what temp is the water moving in your pex?
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Post by dirtdevil on Jul 4, 2019 2:52:20 GMT -8
Typically around 140F but it can go as high as 180F with no apparent problems. I'm not sure what the maximum heat limit for pex is. The pumps run continuously when there is a fire in the box. I live in northern Michigan and we have long hard winters so we usually heat from the middle of October until the middle of May. Cold spring this year. We had to run until the first week in June. I once tried a horizontal grate but quickly pulled that out because if the pump is down for some reason the water in the grate doesn't move. It's not blocked off so I doubt it could create a steam explosion but the banging and clanging noise it makes is scary.
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Post by gadget on Jul 5, 2019 7:02:14 GMT -8
Typically around 140F but it can go as high as 180F with no apparent problems. I'm not sure what the maximum heat limit for pex is. The pumps run continuously when there is a fire in the box. I live in northern Michigan and we have long hard winters so we usually heat from the middle of October until the middle of May. Cold spring this year. We had to run until the first week in June. I once tried a horizontal grate but quickly pulled that out because if the pump is down for some reason the water in the grate doesn't move. It's not blocked off so I doubt it could create a steam explosion but the banging and clanging noise it makes is scary. I have been wondering how well a pex tubing systems would work at only 100F. I would like to run some under the floor for my second level. I have some extra pumps but they are best run at lower temps. I'm not sure how much heat tubing would add at lower temps.
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Post by patamos on Jul 5, 2019 8:33:09 GMT -8
lower temps with lower flow rate will give adequate residency time for thermal transfer. It will be a slower response time, but if you are okay with that kind of longer flywheel then should be no problem
my 2c
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Post by gadget on Jul 5, 2019 20:40:09 GMT -8
lower temps with lower flow rate will give adequate residency time for thermal transfer. It will be a slower response time, but if you are okay with that kind of longer flywheel then should be no problem my 2c Thats good news. I would prefer to use the pumps I have since they are rated for 30,000 hrs and I can run them directly off solar. I also like the idea of having the lower temp water in the house.
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Post by dirtdevil on Sept 25, 2019 14:29:14 GMT -8
My heater project is built in a greenhouse. The heater is complete and just waiting for the money to get some ceramic blanket for the heat riser. One side of the greenhouse will be used for an aquaponics system. It has a poured concrete 600 gallon fish tank in it. I would like to be able to heat the water in the tank to make it more enviro friendly to different kinds of fish. I have a 44 gallon well pressure tank that the diaphragm failed in. It has a base that sits about three inches below the bottom of the tank. I am wondering if I could sit this on top of the 55 gal barrel bell without impacting the performance of the stove itself. Seems like it should not be a problem but I have never run a RMH before.
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Post by patamos on Sept 25, 2019 14:52:46 GMT -8
adding extra height to a barrel/bell tower is not a problem, although i'd be inclined to add a bit more length to the heat riser as well. somewhere in the mix the definition between a bell chamber and downdraft chamber gets blurry, as free stratification of gasses involves a relatively non-turbulent environment. Adding height to the riser makes it behave more like a downdraft or 'contraflow' harvesting system.
my 2 c
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Post by dirtdevil on Sept 26, 2019 3:44:30 GMT -8
Thanks. I have been curious about something else. If the point of the the bell is to cool the gasses from the heat riser so that they drop and are drawn into the exhaust ducting then why wouldn't having the heat riser hitting the bottom of a water tank increase this effect while still providing a direct heat source for water heating. The pressure tank I'm talking about would only pick up ambient heat radiating form the skin of the bell. Better than nothing but certainly not optimal.
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